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Biomedical subjects

S Evans

Publications and source records attributed to S Evans.

At least 235 records · Page 13Linked to original sources
PubMed1992

Regional blood flow in chronic heart failure: the reason for the lack of correlation between patients' exercise tolerance and cardiac output?

BACKGROUND: In patients with chronic heart failure there is no relation between cardiac output and symptom limited exercise tolerance measured on a bicycle or treadmill. Furthermore, the increase in cardiac output in response to treatment may not be matched by a similar increase in exercise tolerance. More important in determining exercise capability is blood flow to skeletal muscle. This implies that the reduction in skeletal muscle blood flow is not directly proportional to the reduction in cardiac output and that there are regional differences in blood flow in patients with heart failure. METHODS: Cardiac output and regional blood flow measured in 30 patients with chronic heart failure were compared with values obtained from 10 healthy controls. Measurements were made at rest and in response to treadmill exercise and were all made non-invasively. RESULTS: Cardiac output was lower in the patients at rest and during exercise. Blood flow in the superior mesenteric and renal arteries was also lower in the patients and represented a different proportion of cardiac output than in the controls. In response to exercise the increase in blood flow to the calf and therefore to skeletal muscle, was reduced in the patients. In the patients there was no correlation between resting cardiac output and blood flow in the superior mesenteric artery, renal artery, or calf. CONCLUSIONS: Because blood flow to skeletal muscle and to the kidneys is likely to be important in determining patients' symptoms this factor may explain why central haemodynamic variables do not correlate with the exercise tolerance in patients with chronic heart failure.

Aged↗
PubMed1992

Histochemical and immunohistochemical characteristics of mast cells in nasal polyps.

In surgically excised nasal polyps, most epithelial mast cells were formalin sensitive, chloroacetate esterase (CAE) negative, and chymase negative. Thus, this represents a population of mast cells not identified by staining for CAE. On the other hand, most stromal mast cells were formalin resistant and CAE positive, and although there was some polyp-to-polyp variability in their content of neutral protease, most of these cells were positive for both tryptase and chymase. The percentage of metachromatic cells in the epithelium and the number of metachromatic cells per unit area of polyp tissue did not correlate with an index of allergy skin test reactivity or the serum IgE concentration. The percentage of mast cells surrounded by pericellular tryptase, suggesting activation/degranulation, was significantly higher in the stroma than in the epithelium. The findings demonstrate differences between the stroma and the epithelium in phenotype and state of activation of mast cells; these are postulated to be due to distinct microenvironmental factors that affect mast cells at these sites.

Acetates↗
PubMed1992

Axonal injury in closed head injury by assault: a quantitative study.

Due to the controversy in the literature regarding the time course of axonal balloon formation in human material, we wished to determine if it was possible to diagnose axonal injury before the development of axonal balloonings. The hypothesis was that the presence of axonal swellings or axonal enlargements associated with a glial reaction could be used as a diagnostic aid in human axonal injury before 12 hours. The brains of eight individuals that survived for less than 48 hours following head injury, and also had evidence of axonal injury using the criteria of Vanezis et al. (1987), were systematically studied by looking at axonal swellings, axonal balloonings, reactive astrocytes, maximum diameter of axonal enlargements and density of axonal enlargements. Controls were eight selected cases without neurological disease. The variables studied were assessed in 25 fields from ten different areas of the brain, using silver stains and immunoperoxidase for glial fibrillary acidic protein (GFAP). Logarithms of one plus the count of each variable were taken from the raw data and these were analysed using percentile distribution and the median, the t-test, Mann-Whitney U test and the Wilcoxon signed rank test. We conclude that quantitation of axonal damage allows the detection of mild degrees of axonal injury that could be overlooked on routine examination, and that the criteria of axonal enlargements, rather than axonal balloonings, are indications of axonal damage, cannot be endorsed with the evidence provided.

Axons↗
PubMed1992

Risk factors for coronary heart disease: a study in inner London.

A survey was carried out among 281 men and women aged between 30 and 64 years randomly selected from five general practices located in the inner London borough of Tower Hamlets, to determine the prevalence of risk factors for coronary heart disease. Smoking and obesity were both more pronounced in Tower Hamlets than in comparable national studies: 51% of men and 44% of women were smokers and 57% of these were smoking 20 or more cigarettes per day. A body mass index of 30 or more was present in 18% of men and 10% of women and a body mass index of 25 or more in 71% of men and 49% of women. Two or more risk factors for coronary heart disease (smoking and/or hypertension and/or raised cholesterol levels) were present in 25% of men and 22% of women. For every person known by their general practitioner to have established cardiovascular disease, there were an additional two people also at risk on the basis of multiple risk factors. In this inner city population the prevalence of cardiovascular risk, for women as well as men, has major resource and organizational implications for primary care. A strategy for change requires action based on graded multiple risks for both men and women.

Adult↗
PubMed1992

Building a healthier workforce.

The European Year of Health has put the construction industry at the top of its agenda. Sarah Evans examines the challenge presented to OH practitioners in this field and looks at the ground-breaking work of OHN, Mike King.

Facility Design and Construction↗
PubMed1991

Mercury in muscle tissue of lesser-spotted dogfish (Scyliorhinus caniculus L.) from the north-east Irish Sea.

This paper reports concentrations of mercury in muscle tissue of lesser-spotted dogfish (Scyliorhinus caniculus L.) from various locations within Liverpool Bay and the north-east Irish Sea. Concentrations of mercury in fish muscle showed distinct spatial variation, with values from the northern sectors of the Irish Sea significantly lower than those for the southern area, particularly sites in Liverpool Bay and around the mouth of the Mersey Estuary. The data support the hypothesis that there are several major populations of lesser-spotted dogfish within the study area, each of which remains quite distinct during seasonal movements. Consequently, exposure to environmental mercury is reflected in muscle concentrations of mercury. Regressions of mercury concentration against fish length showed significant relationships for the majority of sites, with the slope relating to distance from known sources of mercury contamination. Mean mercury concentrations were higher than in corresponding populations of flatfish from the same areas.

Animals↗
PubMed1991

Presence of a cholinergic projection from ventral striatum to amygdala that is not immunoreactive for NGF receptor.

By combining the retrograde axonal transport of a fluorescent dye with nerve growth factor (NGF) receptor or choline acetyltransferase (ChAT) immunocytochemistry, we show that the cholinergic neurons that project most strongly to the basolateral nucleus of the amygdala in the ferret do not possess NGF receptor immunoreactivity in their soma and are situated in the ventral striatum, an area known to receive a massive reciprocal projection from the basolateral nucleus of the amygdala.

Amygdala↗
PubMed1991

Phase I study of the anthrapyrazole biantrazole: clinical results and pharmacology.

In a phase I study the anthrapyrazole biantrazole (Warner-Lambert Company) was given to 41 patients with tumour refractory to existing therapy. The drug was given i.v. weekly for 3 weeks, with a 3-week interval between courses. At the 1st week a full pharmacokinetic study was performed, and at weeks 2 and 3, blood samples were taken at 1 and 6 h following treatment to check for drug accumulation. Biantrazole pharmacokinetics were linear with respect to the AUC (r = 0.924) over the full range of doses studied (4-36 mg/m2) but exhibited large inter-patient variations at each dose level. Elimination was triphasic, comprising two rapid early phases and a long terminal half-life (mean, 14.1 +/- 7.8 h). There was no evidence of drug accumulation over the 3-week treatment period. Approximately 12% of the parent drug was excreted unchanged in the urine together with two non-circulating, more water-soluble metabolites. Biantrazole was well tolerated but did cause moderate emesis at doses of greater than 18 mg/m2 and mild alopecia. The dose-limiting side effect was leucopenia, with no other major toxicity being observed. One patient developed biventricular failure that was not clearly related to biantrazole administration. On the present schedule, the recommended dose of biantrazole is 24 mg/m2. No response were seen in this patient population.

Adolescent↗
PubMed1991

Laparoscopic cholecystectomy in pediatric patients.

Laparoscopic cholecystectomy has gained increasing application as an operative approach for adults with gallbladder disease. We assessed the safety and feasibility of this technique in five pediatric patients with symptomatic cholelithiasis, two of whom had sickle cell disease. With several technical modifications, we found that laparoscopic cholecystectomy was safe and effective in children. This technique permitted early discharge with expedient return to full activity.

Adolescent↗
PubMed1991

The glial reaction in closed head injuries.

The development of the glial reaction in human closed head injury has been investigated using morphometry and statistical analysis. The brains of eight individuals that survived less than 48 h following closed head injury were analysed using immunoperoxidase for glial fibrillary acidic protein (GFAP). Controls were eight patients without neurological disease. The density of reactive astrocytes was estimated in 25 fields in each of 10 different areas sampled bilaterally avoiding the subpial and subependymal zones, and the perivascular white matter. There was great variation between the zones within and between groups, and considerable variation between individuals. The raw data were expressed as logarithms averaged and analysed using the median and non-parametric statistics. The corpus callosum in the head injury group showed the highest densities of reactive astrocytes, particularly in the splenium which achieved statistical significance using the non-parametric tests. This pattern was not reproduced in the control group. Although there was overlap between the head injured and control individuals, the head injury group had relatively higher densities in all zones, and showed an overall increase in the density of reactive astrocytes. This achieved statistical significance in the corpus callosum, the occipital subcortical white matter, and the cerebellum. This study has shown that the glial reaction is often prominent in the corpus callosum irrespective of the presence of a primary lesion although the pattern varies from case to case.

Adult↗
PubMed1991

The use of a low molecular weight heparinoid (Org 10172) for extracorporeal procedures in patients with heparin dependent thrombocytopenia and thrombosis.

We report two cases of heparin induced thrombocytopenia (HIT), in patients who required anticoagulation for extracorporeal procedures (haemodialysis and cardiopulmonary bypass) one associated with recurrent thrombosis of the artificial circuits. Resolution of thrombocytopenia and successful anticoagulation were achieved using a low molecular weight heparinoid (LMWH) Org 10172. Anticoagulation was monitored using estimations of plasma anti-factor Xa activity. These cases demonstrate that LMWH provides safe and effective anticoagulation in patients in whom unfractionated heparin has caused HIT.

Aged↗
PubMed1991

Antibodies to toluene diisocyanate in patients with and without dialysis anaphylaxis.

In a majority of patients with anaphylaxis to dialysis, ethylene oxide has been identified as an etiologic agent. In a significant minority of patients sustaining such reactions, the antigen remains unidentified. Conflicting results have been published with regard to isocyanates as a possible antigen. The authors studied 19 hemodialysis patients with anaphylaxis in whom IgE against ethylene oxide-human serum albumin (ETO-HSA) was not identified (Group 1) and 25 peritoneal dialysis patients without anaphylaxis (Group 2). IgE against toluene diisocyanate-human serum albumin (TDI-HSA) was found in one patient in Group 1, and a similar incidence of IgG against TDI-HSA in Group 1 (16%) and Group 2 (12%) was noted. The results do not suggest that IgE against TDI-HSA is an important cause of dialysis anaphylaxis.

Anaphylaxis↗
PubMed1991

Intravenous vs intraperitoneal sensitizer: implications for intraperitoneal photodynamic therapy.

Photodynamic therapy (PDT) is a potential treatment for peritoneal carcinomatosis. However, little data is available regarding the relative distribution of sensitizer to tumor and intra-abdominal organs, optimal route of sensitizer administration, and maximal tolerated light dose. Tumor and normal tissue sensitizer levels were measured by tissue extraction 3, 24, 48 and 72 h after 10 mg/kg of Photofrin II was given intraperitoneally (IP) or intravenously (IV) in a mouse peritoneal tumor model, and the maximal tolerated PDT light dose determined. Equivalent tumor sensitizer levels were obtained regardless of the route of sensitizer administration. Route of administration, however, did affect the kinetics of tumor sensitizer elimination, with the half-time for elimination (T1/2) 113.6 h for IP drug and 60.6 h for IV drug. Route of administration also affected sensitizer levels in several intra-abdominal organs, resulting in somewhat higher tumor to liver and kidney levels at 24 and 72 h after IP sensitizer administration. Despite these tissue distribution differences, route of sensitizer administration did not significantly affect PDT toxicity or mortality when mice were treated with 630 nm light. The maximum tolerated light dose was 1.04 J/cm2. These parameters will prove helpful in designing large scale animal trials assessing the efficacy and safety of intra-abdominal PDT.

Animals↗
PubMed1991

A 'point' of view--one hospital's experience in the safe handling and disposal of sharps.

Needlesticks had long been a problem at the author's hospital. When the implementation of an in-room sharps disposal system (sharps containers in all patient rooms with the exception of pediatrics, psychiatry and long term care units) did not significantly reduce the numbers of needlesticks, a review of needlestick incident reports pre- and post implementation of the sharps program was conducted. Interestingly enough, recapping was still taking place in spite of education, and the rationale given by most staff was that in certain situations it was safer to recap than not. Second, a review of incidents showed that in both pre- and post implementation data, there were no reported needlesticks to laboratory personnel performing phlebotomy. The reason--the 'safety paddle'. Could a device proven successful in the elimination of needlesticks to laboratory staff be used by other staff to reduce needlesticks throughout the hospital?

Equipment Design↗
PubMed1991

Photodynamic therapy of oncogene-transformed cells.

Photodynamic therapy with dihematoporphyrin ether sensitizes malignant cells to damage by 630 nm light. The in vitro, in vivo photodynamic therapy sensitivity of a cell line transformed by the Kirsten ras oncogene (45342) was studied to establish a new photodynamic therapy model. With the colony formation assay, neither light alone nor dihematoporphyrin ether alone affected 45342 survival. Energy-dependent photodynamic therapy effects were seen in vitro in dihematoporphyrin ether-incubated and light-exposed cells (90% cytotoxicity = 950 joules/m2; 99% cytotoxicity = 1575 joules/m2; p2 less than 0.05). Subcutaneous allografts of 45342 were established in nu/nu mice, and ideal route (intravenous or intraperitoneal) of dihematoporphyrin ether delivery, dihematoporphyrin ether tissue kinetics, and in vivo photodynamic therapy effects were examined. Intravenous administration not only gave higher levels of the sensitizer in various tissues, but also was associated with less variation than the intraperitoneal route. Selective dihematoporphyrin ether retention was documented in the tumors at 24 hours after injection compared with other tissues, and photodynamic therapy with 0.3 W/cm2 to a total dose of 150 joules/cm2 led to progressive coagulative tumor necrosis and tumor regression. These studies confirm that transformed, malignant cells are sensitive to photodynamic therapy, and this model may prove in future studies to increase efficacy to photodynamic therapy (i.e., with dihematoporphyrin ether delivery by monoclonal antibodies).

Animals↗